650 
Journal of Agricultural Research 
Vol. XXIII, No. 8 
the formaldehyde on the mycelium was to produce partial dehydration 
of the cells from which there was slow recovery, or in the case of the 
sclerotia, the formaldehyde killed the outer, but not the inner cells, in 
which case the inner cells developed growth slowly because of their 
position. To illustrate the retarding effect of formaldehyde solutions 
on subsequent growth of sclerotia and mycelium a brief account is given 
of an average treatment with each strength. 
One-to-Fifty Formaldehyde Solution. —Sclerotia were treated in 
the solution, washed aseptically, and plated on nutrient agar. Results 
taken 6 days later showed that sclerotia kept in the solution for io min¬ 
utes made an average colony growth of 8 mm. in diameter, while the 
sclerotia kept in a solution of the same concentration longer than io 
minutes were completely killed. Untreated sclerotia, cultured on the 
same kind of agar for 6 days, developed colonies averaging 32 mm. in 
diameter. 
Ninety particles of mycelium from nutrient agar cultures were treated 
in the solution for different lengths of time, washed and plated on nutrient 
agar (Table II). Only 1 of tie 90 particles showed growth. This one 
remained in the solution for 5 minutes and made a scant growth at the 
end of 11 days. Later the colony developed five sclerotia. The controls 
showed vigorous growth at the end of the first day, each colony producing 
from 2 to 3 dozen sclerotia. 
One-to-One-Hundred Formaldehyde solution. —The method of 
procedure was the same as with the 1-50 solution. After 6 days, sclerotia 
kept in the solution for 10 minutes developed an average colony growth 
26 mm. in diameter, while those exposed for 15 minutes produced an 
